With the development of the information industry, performance requirements for magnetic disk drives have become more sophisticated and more demanding at an accelerated pace. There is a mounting need in the magnetic disk field for a magnetic recording medium capable of reduced size, higher recording densities, and greater reliability.
Typically, a magnetic disk is manufactured using, for example, a glass substrate with fine concentric lines (hereinafter referred to as a “texture”) made on a mirror-polished surface thereof. The glass substrate is then introduced to a vacuum system and an underlayer, a magnetic layer, and a protective layer are formed in sequence through sputtering or some other layer formation method. The surface is then coated with a lubricant and cleaned. In order to reduce spacing between a read/write magnetic head and a magnetic disk, which is indispensable for meeting the recent trend toward higher recording densities, reduction in the surface roughness of the glass substrate is becoming more important, e.g., down to about 2 nm in terms of protrusion height (hereinafter referred to as “Rp”) and about 0.4 nm or less in terms of centerline average roughness (hereinafter referred to as “Ra”). There is another need, on the other hand, for an even greater reduction in the amount of dust and dirt that hampers flying of the magnetic head or an abnormal protrusion exceeding a flying height of the magnetic head. In addition, the permissible size of minor damage (hereinafter referred to as a “scratch”) causing a read/write error is becoming extremely small.
To achieve a reduction in the flying height, a cleaning method is known, in which a tape film having abrasive grains fixed on an abrasive layer (hereinafter referred to as a “cleaning tape”) is pressed against the magnetic disk surface through various techniques. For example, one technique for pressing uses a rubber roller as disclosed in Japanese Patent Office (JPO) Pub. Nos. JP-B-6-52568 and JP-A-2003-136389. Another technique for pressing uses foam as disclosed in JPO Pub. No. JP-A-200′-67655. Still another technique for pressing uses a wiping member that is applied to stroke a lubricant on the magnetic disk surface to thereby eliminate irregularities on a lubricant surface to form a flat surface, which is followed by a tape burnishing process to remove protrusions and dust and dirt as disclosed in JPO Pub. No. JP-A-2-83823. A further known technique uses a cleaning tape as disclosed in JPO Pub. No. JP-A-2000-348337. The cleaning tape has a surface configuration of deep chip pockets and small-diameter abrasive grains. These arrangements are known to help minimize scratches and efficiently remove abnormal protrusions. A still further technique incorporates, as disclosed in JPO Pub. No. JP-A-2002-319127, a pressure suspension system in which a sponge material that is narrower in width than a tape which presses the tape. This results in no load being applied to burr portions on tape ends and eliminates the chance of air directly scattering contaminants across the tape surface. This inhibits occurrence of contamination and reduces the number of minor errors and scratches.
It has been found recently that, in addition to the dust and dirt or the abnormal protrusions that hamper flying the head above the magnetic disk, the lubricant applied to the magnetic disk surface, if deposited on the magnetic head, can impede low flying stability of the magnetic head.
JPO Pub. No. JP-A-2007-58935 discloses a technique, in which a liquid lubricant is applied to a protective layer and, while a magnetic recording medium is being rotated, a processing tape containing solvent therein is simultaneously pressed against an end face and an outer peripheral portion of a data surface of the magnetic recording medium using a tape pressing tool, so that the liquid lubricant can be wiped off. Film thickness of a lubricant layer on the outer peripheral portion of the magnetic recording medium is thereby held to be uniform in thickness, so that the magnetic head can fly in a stable manner.